The present invention relates to a hydrocarbon conversion catalyst and a process for preparing the same. More particularly, it is concerned with a novel hydrocarbon conversion catalyst which exhibits an outstanding effect as a catalytic cracking catalyst for heavy oil containing not less than 0.5 ppm of heavy metals such as, for example, nickel, vanadium and iron, as well as a process for preparing the same.
In the ordinary catalytic cracking process, petroleum hydrocarbons are cracked by contacting with a catalyst to obtain large amounts of light fractions such as liquefied petroleum gas (LPG) and gasoline and small amounts of cracked gas oil, etc., and the catalyst is recycled and reused after removal of coke deposited thereon by burning with air. In such catalytic cracking process, so-called distillates such as, for example, light gas oil (LGO) and heavy gas oil (HGO) obtained from an atmospheric distillation column and vacuum gas oil (VGO) from a vacuum distillation column have heretofore been mainly used as starting oils.
Recently, however, crude oils supplied in the world have become heavier according to classification based on the boiling range, and the structure of the demand for crude oils has changed, and such supply and demand conditions are giving rise to a tendency to excess supply of heavy oils. Consequently, it is now required to use even heavy oils containing distillation residue as starting oils for catalytic cracking.
However, in heavy oils containing distillation residue there are contained metals such as nickel, vanadium, iron, copper and sodium in much larger amounts than in distillates. It is known that these metals are deposited on a catalyst and impede the cracking activity and selectivity severely. More particularly, as the metals are deposited on the catalyst, the cracking percentage lowers to the extent that a desirable cracking percentage is substantially not attainable, while the amount of hydrogen and that of coke produced are remarkably increased, thus making the operation of the apparatus difficult, and at the same time the yield of desirable liquid products decreases.
Generally, catalysts available as catalytic cracking catalysts for heavy oils, like ordinary catalytic cracking catalysts using distillates as starting materials, comprise a combination of Y type zeolite and an amorphous silica-alumina matrix. In such conventional catalysts, however, it is necessary to reduce. the surface area of the matrix in order to improve the resistance to metals, and even such reduction of the surface area is done, the catalytic performance is still unsatisfactory.